biological psychology ch. 14

biological rhythms, sleep, & dreaming

circadian rhythms

functions of a living organism that display a rhythm of about 24 hours, generated by an endogenous clock.

diurnal

active during the light

nocturnal

active during the dark

free-running animal

an animal who maintains its own cycle without external cues

period

the interval of time between two similar points of successive cycles, such as sunset to sunset. (may not be exactly 24 hours)

phase shift

the shift in activity in response to a synchronizing stimulus, such as light or food

what part of the brain is the biological clock located in?

suprachiasmatic nucleus (SCN)

What happens if there is a lesion in an animals suprachiasmatic nucleus (SCN)?

circadian rhythms are disrupted and there is no longer a predictable sleeping pattern.

Where is the endogenous period (free-running period) generated?

suprachiasmatic nucleus (SCN)

infradian

a biological rhythm that is longer than a day, but occur less frequently (body weight, reproductive cycles)

In the absence of cues, how long is the free-running period for humans?

25 hours

non-REM sleep (NREM)

can be divided into 3 stages and is characterized by lack of rapid eye movements.

rapid-eye-movement sleep (REM)

characterized by small-amplitude, fast-EEG waves, no postural tension, and rapid eye movements.

The pattern of activity in an awake person:

dominated by a mix mof high frequency and low amplitude waves (beta activity/desynchronized EEG)

stage 1 sleep

begins when vertex spikes appear, lasts several minutes

• heart rate slows, muscle tension decreases, eyes roll about

stage 2 sleep

defined by waves of 12-14 Hz that occurs in bursts, sleep spindles. K-complexes appear- sharp negative EEG potentials.